Gas detectors may be carried by workers in environments where there is potential for harmful gases. The gas detectors may be periodically tested and/or calibrated to ensure that the detector is working properly. This may be done using a gas testing system operable to supply a sample gas to the detector and analyze the response of the gas detector. In some workplaces, the testing may occur while a user is wearing other protective gear, such as gloves, suits, helmets, respiratory equipment, etc.